Anatomy of the Heart

What is the purpose of a heart?  Not all organisms have a heart, what is the advantage of having a heart?

Different kinds of hearts

Aortic Arches  The “hearts” of the earthworm  Blood is pumped by the dorsal vessel into the aortic arches

2 chambered heart (fish)  Blood moves in one direction  2 chambers – atrium and ventricle  Blood goes to gills to be oxygenated after leaving ventricle

3-chambered heart (frog)  2 atriums, and 1 ventricle  Oxygenated blood comes into the left atrium, and deoxygenated blood comes in from the right atrium.  Both atria lead to the same ventricle

4 Chambered heart (Human)  Has 2 atriums, and 2 ventricles  4 valves prevent blood from going the wrong way.  Each side receives and sends blood to its respective circuit

Think, pair, share  Think of the advantages disadvantages of each heart  Pair up (with the person beside you) and discuss you answers  Share your answers with the class

Advantages/disadvantages  2 chambered heart  Low on energy  Only works with gills  3 chambered heart  Low on energy  Mixing of blood limits organism’s activity  4 chambered heart  Very efficient, transports the most oxygenated blood to the cells  High energy cost

How does it work?  2 stages of the heart  Systole – heart contraction  First the atriums, then the ventricles  Diastole heart at rest

Human Heart